The World Happiness Report puts Australia at No 10 out of 156 countries it regularly evaluates for the satisfaction and cheerfulness of its citizens.

That's down one spot from last year.

Sweden elbowed its way into our spot.

It's still a Top 10 result. It's just the advancing bit we're having a problem with.

So where in the world are the most happy people?

Cold, soggy, dark Finland.

The World Happiness Report assesses factors such as life expectancy, social support and corruption.

Rounding out the top 10 are Denmark, Iceland, Switzerland, the Netherlands, Canada, New Zealand, Sweden and Australia.

The United States is also going backwards, fast. It fell to 18th place from 14th last year.

"The US happiness ranking is falling, in part because of the ongoing epidemics of obesity, substance abuse, and untreated depression," said Jeffrey D. Sachs, another coeditor of the report.

The unhappiest nation was Burundi whose leader, President Pierre Nkurunziza, changed his title from "eternal supreme guide" to "visionary" just this week.

Snowman World Ice Restaurant in Llapland Finland. Despite the cold and weather, Finland has figured out how to convert wealth into wellbeing.

NORDIC GOLD

Finland is one of the world's northernmost countries stretching some 1160 kilometres from north to south, the sun does not set for 73 consecutive days during summer at Finland's northernmost point. During the winter months, the sun doesn't rise at all for 51 days in Lapland, northern Finland.

This is often blamed for high rates of depression

Yet it has emerged as the happiest place to live.

"Well, our politics and our economics. I think the basics are quite good in Finland," said Sofia Holm, 24-year-old resident of Helsinki, the country's capital. "So, yes, we have the perfect circumstances to have a happy life here in Finland."

And that's not forgetting other plentiful attractions like skiing and saunas and, for children of all ages, Santa Claus.

"It's a great thing to live in the happiest country although it's snowing and we are walking in this wet snow," said Helsinki resident Inari Lepisto, 28. "Yes, we have many things that make me happy."

Meik Wiking, CEO of the Copenhagen-based Happiness Research Institute, said the five Nordic countries that reliably rank high in the index "are doing something right in terms of creating good conditions for good lives," something newcomers have noticed.

The happiness revealed in the survey derives from healthy amounts of both personal freedoms and social security that outweigh residents having to pay "some of the highest taxes in the world," he said.

"Briefly put, (Nordic countries) are good at converting wealth into wellbeing."

rmed protesters from the Bureau of American-Islamic Relations (BAIR), stage a demonstration in front of the Islamic Association of North Texas at the Dallas Central Mosque on December 12, 2015 in Richardson, Texas. Picture: AFP

UNLUCKY COUNTRY

The report cited several factors to explain the plunge in the United States' ranking.

"The US is in the midst of a complex and worsening public health crisis, involving epidemics of obesity, opioid addiction, and major depressive disorder that are all remarkable by global standards," the report said.

It added that the "sociopolitical system" in the United States produces more income inequality - a major contributing factor to unhappiness - than other countries with comparatively high incomes.

The US also has seen declining "trust, generosity and social support, and those are some of the factors that explain why some countries are happier than others," Wiking said.

It notes the world's obesity epidemic epicentre is geographically and culturally focused on the United States.

Mexico is one of the next worst, and it borders the US. But countries with close business and cultural ties (particularly through advertising), such as Australia, the UK, Canada and New Zealand, are also becoming increasingly unhealthy.

A protester near the exhibition building in Melbourne. While immigration is a heated debate, those that do settle here find their lives much improved. Picture: David Crosling

IMMIGRATION FACTOR

For the first time, the annual report published by the UN Sustainable Development Solutions Network also evaluated 117 countries by the happiness and wellbeing of their immigrants.

In 2015, more than a million migrants entered Europe, and a few thousand made it to Finland, a relatively homogenous country with about 300,000 foreigners and residents with foreign roots, out of its 5.5 million people. Finland's largest immigrant groups come from other European nations, but there also are communities from Afghanistan, China, Iraq and Somalia.

It noted Australia had the highest percentage of foreign-born citizens, coming it at 28 per cent where the world average is 20 per cent.

Helliwell noted that all the countries in the Top 10 scored highest both in overall happiness and regarding the happiness of immigrants.

He said a society's happiness seems contagious.

"The most striking finding of the report is the remarkable consistency between the happiness of immigrants and the locally born," he said. "Those who move to happier countries gain, while those who move to less happy countries lose."